Actinium Advances Actimab-A Trials In Combination With PD-1 Inhibitors For Solid Tumors

(RTTNews) - Actinium Pharmaceuticals, Inc. (ATNM) Tuesday has launched a clinical program evaluating Actimab-A in combination with the PD-1 inhibitors pembrolizumab - KEYTRUDA and nivolumab OPDIVO.

These immunotherapies generated $38.8 billion in 2024 across various solid tumor indications but face efficacy limitations due to Myeloid-Derived Suppressor Cells - MDSCs, which help tumors evade immune detection. Actimab-A targets CD33, an antigen expressed by MDSCs, aiming to enhance the effectiveness of PD-1 inhibitors by depleting these immune-suppressive cells.

The program includes controlled, head-to-head clinical trials comparing Actimab-A with PD-1 inhibitors versus PD-1 inhibitors alone in patients with head and neck squamous cell carcinoma - HNSCC and non-small cell lung cancer - NSCLC.

The trials will assess safety, overall response rate - ORR, progression-free survival - PFS, overall survival - OS, and biomarker data, including CD33+ MDSC depletion and T-cell activity. Initial proof-of-concept data is expected in late 2025.

Actimab-A, Actinium's lead radiotherapeutic, delivers Actinium-225, a potent alpha-emitter radioisotope designed to induce lethal DNA damage in targeted cells. It has been studied in over 150 patients with acute myeloid leukemia - AML and is advancing toward a registrational trial in relapsed/refractory AML in 2025.

Actinium's leadership views this program as a potential breakthrough for patients whose cancer progresses despite PD-1 inhibitor treatment. The company estimates that over 500,000 patients could benefit from this approach, reinforcing Actimab-A's potential as a leading targeted radiotherapy.

ATNM is currently trading at $1.225 or 5.7692% lower on the NYSE.